Layout test fast/images/low-memory-decode.html is timing out on the GTK port since it was added in 218826 "REGRESSION (AsyncImageDecoding): A tab with the WWDC keynote paused is killed for using excessive power (Image thrashing)".
I see it's skipped on mac-wk1 with a comment "requires wk2 speculative tiling". Perhaps only Mac port can handle image decoding under memory pressure?
I'll add a timeout expectation.
Carlos Lopez fixed this in r232881.